Examination of Enhancing Efficiency of Axial Gap Motor in High Speed and High Torque Region by Adopting Neodymium Bonded Magnet

摘要

In recent years, more than half of the electric power generated in the country is being consumed by motors. Therefore, high performance motors are desired especially for industrial applications. In addition, it is desirable to reduce motor size. Recently, motors called axial gap type have been proposed and researched to achieve both high torque and small size. Axial gap motors are generally suitable for applications requiring flat shape such as a disk. Conventional axial gap motors frequently employ Nd sintered permanent magnets (PMs) to achieve high torque. However, axial gap motors with Nd sintered PMs are not very efficient at high rotational speed due to the eddy current loss arising in the PM. Axial gap motors that use ferrite PMs have also been proposed, but torque density is low. In this paper, an axial gap motor using Nd bonded PMs is proposed to achieve high efficiency in the high-speed and high-torque region. The proposed axial gap motor using Nd bonded PM is compared with other axial gap motors employing Nd sintered PM and ferrite PM through 3D-FEA and experiments. Consequently, it was found that the Nd bonded PM is more effective in enhancing the efficiency of an axial gap motor in the high-speed and high-torque region, compared with Nd sintered PM and ferrite PM.